The present invention relates to a technique for forming a passenger restraint belt used for restraining a passenger when a vehicle accident occurs.
A conventional technique for forming a passenger restraint belt has been described, for example, in Japanese Unexamined Patent Application Publication No. 2004-315984 (the '984 publication) (incorporated by reference herein). The '984 publication discloses the possibility of forming a seat belt having superior compactness and comfort for use as a long passenger restraint belt by improving filament yarn bundles used for the seat belt, the woven configuration of the bundles and the like.
When this type of seat belt is designed, a basic property of rigidity capable of restraining a passenger in the case of a vehicle accident is required. Also, a reduction in the weight of the seat belt is also desired in consideration of the comfort of the passenger when the seat belt is worn as disclosed in the above the '984 publication and the properties of withdrawing the seat belt from a retractor. In order to reduce the weight of the seat belt, it is conceived that the number of filaments forming the seat belt may be reduced. By a method for simply reducing the number of filaments, the reduction in weight may be achieved; however, the decrease in rigidity caused by the reduction in the number of filaments may become a concern. As a result, the basic property of restraining a passenger may not be sufficiently obtained in some cases.
An object of a disclosed exemplary embodiment is to provide an effective technique for simultaneously achieving the increase in rigidity of a passenger restraint belt which is installed in a vehicle and the reduction in weight of the restraint belt. The disclosed exemplary embodiments may be applied to a technique for forming a seat belt or a safety belt, which is used as a means for restraining a passenger in a vehicle such as an automobile.